feat(acp): advertise and switch llm models

packages/llm/llm-pi-ai/README.md

@@ -26,6 +26,8 @@ Configure credentials and deployment-specific transport settings per provider. O
 
 Each provider name must exist in pi-ai's installed catalog and may appear only once in this plugin instance. Registration with `ctx.llm` is atomic: a collision with any provider route already owned by another adapter fails plugin loading without registering the remaining routes. Model ids are not lifecycle config; an unknown model fails before any provider request with `LlmError('UNKNOWN_MODEL')`.
 
+The adapter exposes each configured provider's installed pi-ai models through `ctx.llm.listModels(provider)`. This is provider-neutral selector metadata derived from `getModels(provider)`; request-time resolution still performs the authoritative catalog lookup, so discovery does not create a second model registry.
+
 Supported profile fields are `provider`, `apiKey`, `baseURL`, `headers`, `reasoning`, `thinkingBudgets`, `cacheRetention`, `transport`, `timeoutMs`, `websocketConnectTimeoutMs`, `maxRetries`, and `maxRetryDelayMs`. They map to pi-ai's common stream options. Harness app attribution wins a conflicting configured header name.
 
 ## Provider/model routing and replay

packages/llm/llm-pi-ai/src/adapter.ts

@@ -15,7 +15,7 @@ import type {
   SimpleStreamOptions,
 } from '@earendil-works/pi-ai'
 import { attributionHeaders, LlmAdapter, LlmError } from '@deepseek-ai/dsh-llm'
-import type { GenerateOptions, StreamChunk } from '@deepseek-ai/dsh-llm'
+import type { GenerateOptions, LlmModelInfo, StreamChunk } from '@deepseek-ai/dsh-llm'
 import type { PiAiProviderProfile } from './config.ts'
 import { toPiContext } from './context.ts'
 import { toStreamChunks } from './stream.ts'
@@ -65,6 +65,18 @@ export class PiAiAdapter extends LlmAdapter {
     this.profiles = new Map(options.profiles.map(profile => [profile.provider, profile]))
   }
 
+  override listModels(provider: string): Promise<readonly LlmModelInfo[]> {
+    const profile = this.profiles.get(provider)
+    if (profile === undefined) {
+      return Promise.reject(new LlmError(`pi-ai adapter does not own provider "${provider}"`, 'NO_ADAPTER'))
+    }
+    return Promise.resolve(getModels(profile.provider as KnownProvider).map(model => ({
+      provider,
+      id: model.id,
+      name: model.name,
+    })))
+  }
+
   async * stream(options: GenerateOptions): AsyncIterable<StreamChunk> {
     if (options.stop !== undefined) {
       throw new LlmError('llm-pi-ai does not support GenerateOptions.stop', 'UNSUPPORTED_OPTION')

packages/llm/llm-pi-ai/tests/adapter.spec.ts

@@ -186,9 +186,23 @@ describe('provider profile lifecycle', () => {
     const fiber = await ctx.plugin(LlmPiAi, {
       providers: [{ provider: 'openai' }, { provider: 'anthropic' }],
     })
-    expect(ctx.llm.providers()).toEqual(['openai', 'anthropic'])
+    expect(ctx.llm.listProviders()).toEqual([
+      { id: 'openai', name: 'openai' },
+      { id: 'anthropic', name: 'anthropic' },
+    ])
     await fiber.dispose()
-    expect(ctx.llm.providers()).toEqual([])
+    expect(ctx.llm.listProviders()).toEqual([])
+  })
+
+  it('exposes the installed pi-ai model catalog through provider-neutral metadata', async () => {
+    const ctx = new Context()
+    await ctx.plugin(LlmService)
+    await ctx.plugin(LlmPiAi, { providers: [{ provider: 'openai' }] })
+    const models = await ctx.llm.listModels('openai')
+    expect(models.find(model => model.id === 'gpt-4.1')).toEqual({
+      provider: 'openai', id: 'gpt-4.1', name: 'GPT-4.1',
+    })
+    expect(models.every(model => model.provider === 'openai')).toBe(true)
   })
 
   it('accepts absent credentials for pi-ai ambient authentication', async () => {
@@ -210,6 +224,7 @@ describe('provider profile lifecycle', () => {
 
   it('constructs the adapter directly and rejects routes it does not own', async () => {
     const adapter = new PiAiAdapter({ profiles: [{ provider: 'openai' }] })
+    await expect(adapter.listModels('anthropic')).rejects.toMatchObject({ code: 'NO_ADAPTER' })
     await expect((async () => {
       for await (const _chunk of adapter.stream({ provider: 'anthropic', model: 'claude-sonnet-4', messages: [] })) { /* drain */ }
     })()).rejects.toMatchObject({ code: 'NO_ADAPTER' })